The present invention relates to a power supply controller used in various devices including, for example, a photo printer for printing a picture on a recording medium (photographic paper).
As a safety measure for an occurrence of a failure in a power supply system of a device, a UPS (uninterruptible power supply) is mainly used. Specifically, when a failure occurs in a device including the UPS, a power supply is switched to the UPS so as to automatically shut the device down to prevent a malfunction and the like. However, since a photo printer such as a Minilab system has a large power capacity, the use of the UPS for the photo printer significantly increases cost. Therefore, the complete backup by the UPS has a limit.
Moreover, in some problems occurring in the power supply system, various situations sometimes occur in an unrepeated fashion. For example, if a failure such as an instantaneous blackout occurs in a power supply system of the above mentioned photo printer while photographic paper is being exposed to light with a laser light source, there is no guarantee that a printed image being developed on the photographic paper at that time is correctly output. As a result, if a photo print is passed to a customer while the occurrence of the failure in the power supply system remains unnoticed, such a problem is discovered only after the customer makes a compliant.
Moreover, it sometimes happens that a power supply system has a breakdown while a control system is normal. In contrast, there is a case where the control system has a breakdown while the power supply system is normal. The latter case induces a more serious problem in view of safety. In this case, a mechanical component in the device sometimes becomes out of control to cause runaway, thereby damaging the system.
Furthermore, the cause of a failure in a power supply system is difficult to identify. Therefore, in many cases, it takes a considerable time to determine the cause. For such a reason, when a failure occurs, a power supply device, a control board and the like considered to be the cause of a phenomenon at the occurrence of the failure are entirely replaced in most of the cases. Therefore, a task of a serviceman who replaces the components increases. Moreover, since the corresponding components are all replaced without identifying the cause of the failure, there arises another problem in that repair cost is disadvantageously increased.
On the other hand, a technique of using a software to self-diagnose a power supply system is known. According to this technique, after a device is powered ON, a software for self-diagnosis operating on the device is started to self-diagnose a power supply system to display the result of diagnosis on a display device such as a display. However, if a failure occurs in the power supply system, the device itself is not activated. Therefore, the cause of a failure in the power supply system cannot be identified in the self-diagnosis using a software.
As a conventional technique related to the technical field of the present invention, JP 2004-119516 A can be cited. JP 2004-119516 A relates to a power monitoring apparatus and the like for monitoring a failure in a power supply. JP 2004-119516 A discloses the following power monitoring apparatus. The power monitoring apparatus monitors a voltage fluctuation range of a power supply and a duration of voltage fluctuations within the voltage fluctuation range. The power monitoring apparatus looks up a voltage failure rank table for determining a voltage failure rank of the power supply to determine the power supply failure rank of the power supply based on the voltage fluctuation range and the duration obtained as the result of monitoring. The power monitoring apparatus sends a power supply failure signal indicating the thus determined power supply failure rank to a destination of the power supply voltage so as to efficiently implement the operation at the destination of the power supply voltage.